The field of the present invention generally relates to bar code scanning apparatus. More particularly, the field of the present invention relates to a method and apparatus for preferentially aligning the surfaces of an item with respect to a predetermined locus of positions defining an optimal scanning path for decoding a bar code label and a system for providing display of alphanumeric data and/or pictorial images or the like corresponding to the item being scanned.
Bar code scanners are well known for scanning the universal product code ("UPC") and other types of bar codes on packages or containers, particularly in retail stores. Generally, in retail stores, bar code scanners are set up at check-out stands or are built into a horizontal check-out counter so that a laser beam is scanned up through a transparent window, defining a number of different scan lines. Normally, packages are placed by the customer on a counter, deck or conveyor. A check-out person then takes each package, visually locates the UPC or other bar code label on a surface of the package and moves the package through the laser's scanning area. One disadvantage of this technique is that the label must first be found and then the package must be held in a particular orientation in order to effect an accurate reading by the laser scanner decoding the bar code lines as the bar code moves through the scanning area. Misalignment of the bar code lines, or inadvertent movement of the package during the scanning operation can result in a misreading (or a non-read) of the bar code.
Conventional attempts to minimize or eliminate the participation of check-out personnel include a device such as described in U.S. Pat. No. 4,939,355. There, an item transported by a moving conveyor is subjected to a complex series of different scan patterns approaching from different sides of the item. This scanning requires a large depth of field for the scan beams. The item to be scanned is placed in any orientation on the scan belt. A scanning means generates scan lines in an X configuration for reading the object in virtually any orientation. Due to the infinite variations in product sizes, irregularities of shapes and differing locations of a bar code label on an item, conventional scanning methods too frequently fail to achieve a first successful read on the pass of the item scanned, which requires rescanning to obtain the data associated with the bar code label being decoded.
Additionally, conventional methods for bar code scanning provide the customer with an itemized listing, such as receipt list, of the items which were scanned. There is a time lag between the time that the items are scanned and the point at which the customer receives the itemized list. This time lag often results in a lack of customer recognition of the items and their associated prices. The lack of recognition inherent in a list, disassociated from the items as they are moving on a scanning path, may lead to customer misunderstanding and may slow down the check-out process at a retail point of sale.
Another problem associated with conventional automated scanning systems involves security. For example, in the method described in U.S. Pat. No. 4,676,343, the customer must look for each label and then scans the item in the conventional manner. The item is then placed on a conveyor belt for transport and item verification. This system is very slow because of the inexperience of the customer and because of the difficulty in finding the label. This method also does not provide adequate security because the customer can place a higher priced similar item on the belt.
An additional problem in a conventional automated scanning system is a substantial number of "no reads" when an item is not positioned properly in the scanning region. When an item has an irregularly shaped surface, the rate of no-reads tends to be higher for conventional automatic scanning systems.